Allen Pomeroy

Blog of an IT security specialist .: beta :.

Accessing Ubuntu desktop from Mac Snow Leopard

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Accessing my Ubuntu 9.04 Gnome desktop from the built in Mac OS X 10.6.2 VNC viewer took a bit of tweaking on the Ubuntu Gnome side. I have an OpenVPN SSL tunnel between the Mac and the Ubuntu desktop, however a SSH tunnel could also be used to protect the VNC session. In this post, I’ll just cover the VNC server setup assuming a secure connection between the Mac and the desktop.

Initially I followed the guidance at sanity, inc.”How to OS X Leopard Screen Sharing with Linux“, on Ubuntu I installed tightvnc:

apt-get install tightvncserver

Then tested it out by starting up the vnc server on the Ubuntu system as the user I want to run the remote session as:

tightvncserver -geometry 1024x700 -depth 24 :1

As tightvncserver starts up the VNC service, it will check for a .vncpasswd file in the user home directory. If it doesn’t exist, you will be prompted for a password to use to protect the remote session.  Note VNC is not designed to be used for multi-user remote access.
On the Mac, rather than use Bonjour to automatically discover the Ubuntu screen sharing service, I just referred to the VNC session directly within Finder which invokes the built in VNC viewer. Enter the VNC session password when prompted and the Ubuntu desktop is displayed. connect-to-server Within Finder, either use Go -> Connect to Server or Apple-K to bring up the Connect to Server window.  The server address is the URL that points to the Ubuntu VNC instance vnc://10.10.1.2:5901 where the port is 5900 + the display number specified when starting up the tightvncserver (5901).

This all worked fantastic, except for the keyboard mapping within Gnome – it was scrambled.  After googling several possible solutions, the only one that was successful for me was to disable the keyboard plugin in Gnome

Amit Gurdasani wrote on 2008-04-28: #51

I’ve also encountered this issue with TightVNC and the hardy release. My solution was to capture the xmodmap -pke output as ${HOME}/.Xmodmap at the login screen (DISPLAY=:0 XAUTHORITY=/var/lib/gdm/:0.Xauth sudo xmodmap -pke > ${HOME}/.Xmodmap). When gnome-settings-daemon starts up and finds an .Xmodmap, it asks if it should be loaded — I answer yes. As a side effect, if gnome-settings-daemon were to be restarted without the .Xmodmap, it’d scramble the keyboard layout again. With an .Xmodmap in place, it’ll load the .Xmodmap every time.

Due to another issue (#199245, gnome-settings-daemon crashing with BadWindow every time a window is mapped), I disabled the keyboard plugin using gconf-editor, at /apps/gnome_settings_daemon/plugins/keyboard. Since it’s not being loaded, I suspect it might not garble the layout even if I remove the .Xmodmap now.

So maybe disabling the keyboard plugin is a better fix.

On the Ubuntu system, invoke the Gnome configuration editor (gconf-editor on command line), then navigate to apps -> gnome_settings_daemon -> plugins -> keyboard uncheck the Active keyword.  Kill the VNC daemon and relaunch it – problem fixed.

pkill vnc
tightvncserver -geometry 1024x700 -depth 24 :1

Various methods exist to automatically start and kill the VNC server, but for now this will do it for me.

  • Author: admin
  • Published: Jan 9th, 2010
  • Category: notes
  • Comments: None

bash_history

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Here’s some notable cli entries that I refer to occassionally:

Mac OS X:

sudo /usr/sbin/sysctl -w net.inet.ip.fw.enable=1
sudo /sbin/ipfw -q /etc/firewall.conf
sudo ifconfig en0 lladdr 00:1e:c2:0f:86:10
sudo route add -net 10.2.1.0/24 10.3.1.1

Linux:

IMAP mailstore migration .. again

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So last weekend, I discovered that Spamhaus decided it would be a good idea to place all of the public IP addresses for Slicehost (my Linux VPS hoster) into their Spamhaus block list (SBL). This covered both my slice in Dallas and the one in St. Louis – meaning an impressive chunk of inbound mail to my domains was being trashed by the sending MTA and an even bigger chunk of my outbound mail was being outright rejected since the sending IP’s were on the SBL.  Slicehost worked hard to convince Spamhaus to recind the blocklist, so the Slicehost IP’s got moved over to the less-nasty-but-you’re-still-probably-a-spamming-dirtbag Policy Block list (PBL) assuming affected IP owners would request to be removed from that list.

Sample query to see if you’re on any Spamhaus block list:  http://www.spamhaus.org/query/bl?ip=10.11.12.13

It seems it’s time to relinquish the care and feeding of my own Postfix mail system and turn to a hosted solution.  This means I need to migrate about 5GB of IMAP store to another site (again).  Last time I did a wholesale migration, I used imapsync to make the transition painless. In the code example below, an SSL connection to the IMAPS server at imap-server.sourcedomain.com is made with username@sourcedomain.com and the password stored in the plaintext file secret1. An SSL connection is made to the target system (which happens to be the server on which the imapsync tool is running, but could just as easily be another IMAPS server somewhere on a network accessible to the host where imapsync is running). The –delete and –expunge1 arguments will clean the successfully moved messages from IMAP store #1 .. so be sure you have your messages on the target successfully! Imapsync can be run iteratively to ensure you have got all the messages from your source.


/usr/bin/imapsync \
--host1 imap-server.sourcedomain.com \
--ssl1 \
--authmech1 LOGIN \
--user1 username@sourcedomain.com --passfile1 secret1 \
--host2 127.0.0.1 --user2 username@targetdomain.com --passfile2 secret2 \
--ssl2 \
--delete --expunge1 \
--buffersize=128

And one can use the

--dry

option to just test the process but not actually move any of the messages.

So that’s it – I’m about half way though migrating my current IMAP stores over to a hosted mail solution, so that I don’t need to keep up with the increasing level of care and feeding that running your own mail service requires.  Before I get too many darts about that .. I first started running my own personal MTA in 1995, adding spam and av filtering over time, and adding substantial redundancy (servers, sites, storage) so I could rely on it and fix things that broke as I had time rather than right when they broke (which was always at a bad time).  My new hosted solution takes over from two VPS servers running Postfix, Spamassassin, ClamAV, Greylisting with the IMAP store replicated across data centers in different states (15 minute rsyncs).  So soon, the (hopefully) last Allen Pomeroy owned and operated MTA can be turned off, while I get to work on fun stuff, rather than figuring out why my email is bouncing.  :-)

Building a web security lab (with VMware Fusion)

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Problem: VMware machines load boot loader immediately, no BIOS banner, so can’t get into BIOS to alter boot settings.
Solution: Edit the vm’s .vmx file and add the line:

bios.bootDelay = "5000"

which adds a 5000 millisecond (5 second) delay to the boot, or add:

bios.forceSetupOnce = "TRUE"

to make the VM enter the BIOS setup at the next boot.

Problem: VMware Fusion 3.0 doesn’t give a way to edit the virtual network settings via the GUI.
Solution: To change the subnet used by the NAT or HostOnly networks, go root in Mac OS X and edit

/Library/Application Support/VMware Fusion/networking

and set the following lines to the subnets desired:

answer VNET_1_HOSTONLY_SUBNET 192.168.35.0
answer VNET_8_HOSTONLY_SUBNET 10.10.1.0

To add additional custom isolated host only VLANs, also edit the networking file and add additional VNET definitions. There can apparently only be 8 VLANs with VLAN 1 and 8 already pre-defined.

answer VNET_2_DHCP no
answer VNET_2_HOSTONLY_NETMASK 255.255.255.0
answer VNET_2_HOSTONLY_SUBNET 10.10.21.0
answer VNET_2_VIRTUAL_ADAPTER yes
answer VNET_3_DHCP no
answer VNET_3_HOSTONLY_NETMASK 255.255.255.0
answer VNET_3_HOSTONLY_SUBNET 10.10.22.0
answer VNET_3_VIRTUAL_ADAPTER yes
answer VNET_4_DHCP no
answer VNET_4_HOSTONLY_NETMASK 255.255.255.0
answer VNET_4_HOSTONLY_SUBNET 10.10.23.0
answer VNET_4_VIRTUAL_ADAPTER yes

Now create your vm with as many network interfaces as you have separate VLANs (vnet) then edit the node.vmx vm configuration file and change the interfacename.connectionType to custom, and define the VLAN (vnet) that interface will attach to:

#ethernet0.connectionType = "nat"
ethernet0.connectionType = "custom"
ethernet0.vnet = "vmnet3"

Also realize that VMware will take the .1 host address on each vmnet – so you cannot assign .1 to any of your VMs.

Problem: Ubuntu 9.10 persistent network configuration (stores the MAC address of network adapters), so if you copy a machine, by default Ubuntu will setup a new logical adapter (eth1) since the MAC address has changed (when you answer I Copied It in VMware).
Solution: Tell VMware you copied the machine, so it will chose a unique MAC address. Boot Ubuntu into single user mode (another article on that to follow) then edit the MAC address associated with eth0.

sudo vi /etc/udev/rules.d/70-persistent-net.rules

find the stanza of the network interface in question (NAME=”eth0″) and set the following ATTR tag to the new MAC address:

ATTR{address}=="new-mac-address-here"

  • Author: edhacker
  • Published: Sep 8th, 2009
  • Category: tech
  • Comments: 1

Sifting through Checkpoint FW1 logs

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Recently I found myself in the unhappy position of needing to sift through slightly more than a billion Checkpoint Firewall-1 log lines, looking for specific patterns of access. The problem was that many of the exported fwm log files had differing column positions and there had been many ruleset changes over the course of 11 months worth of log data. Many of the excellent FW1 log summarization tools (such as Peter Sundstrom’s fwlogsum) didn’t handle the hundreds of files and differing column positions.

The final scripted solution was processing over 11,000 lines/second .. and still took over 23 hours for the first run.

Log file exports via fwm logexport can have variable column positioning, except for record ID number “num”, which is *always* column number one.  I see three viable alternatives to the changing column position in the ASCII log files exported via fwm – so we can automate the log processing:

  • Export the FW1 log file to ASCII via
    fwm logexport -i fw1-binary-logfile -o fw1-ascii-logfile.txt -n -p
    1. Parse the header line (line #1) of every log file and dynamically map (rearrange) the columns to a pre-determined standard in memory before further processing (painful, expensive)
    2. Tell Checkpoint fwm to export in a fixed column ordering
        create
        logexport.ini
        and place in
        $FWDIR/conf directory
        eg. fwmgmtsrv:
        C:\WINDOWS\FW1\R65\FW1\conf
        logexport.ini:
        [Fields_Info]
        included_fields = num,date,time,orig,origin_id,type,action,alert,i/f_name,
        i/f_dir,product,rule,src,dst,proto,service,s_port,xlatesrc,xlatedst,
        nat_rulenum,nat_addtnl_rulenum,xlatesport,xlatedport,user,
        partner,community,session_id,ipv6_src,ipv6_dst,
        srckeyid,dstkeyid,CookieI,CookieR,msgid,elapsed,
        bytes,packets,start_time,snid,ua_snid,d_name,id_src,ua_operation,
        sso_type_desc,app_name,auth_domain,uname4domain,wa_headers,
        result_desc,r_dest,comment,url,redirect_url,enc_desc,e2e_enc_desc,
        auth_result,attack,log_sys_message,
        rule_uid,rule_name,service_id,resource,reason,cat_server,
        dstname,SOAP Method,category,ICMP,message_info,
        TCP flags,rpc_prog,Total logs,
        Suppressed logs,DCE-RPC Interface UUID,Packet info,
        message,ip_id,ip_len,ip_offset,fragments_dropped,during_sec
    3. Use OPSEC LEA tools to extract event log records instead of export via fwm logexport

    Once the ASCII log files are available for processing, my fw1logsearch.pl script can be used to find complex patterns of interest.  Any matching records found by fw1logsearch will be output with an initial FW1 header line so that fw1logsearch can be used iteratively, to build very complex search criteria.  fw1logsearch can also write out a discard file allowing completely negative logic searches resulting in 100% of the input data separated into a match file and a didn’t match file.  Some examples of how I’ve used it are shown here:

    gunzip -c fwlogs/2009*gz | \
    fw1logsearch.pl --allinclude \
    -S '10\.1\.1[1359]\.|10\.2\.1[01]\.|192\.168\.2[245]\.' \
    -d '10\.1\.1[1359]\.|10\.2\.1[01]\.|192\.168\.2[245]\.' \
    -p '^1310$|^1411$|^1812$|^455' | \
    fw1logsearch.pl -S '192\.168\.22\.14$|10\.2\.11\.12$' |\
    fw1logsearch.pl --allexclude \
    -S '^192\.168\.24\.12$' -P '^1310$' --rejectfile 192-168-24-12-port-1310.txt

    Line by line:
    1. Unzip the compressed ASCII log files, feed them to the first instance of fw1logsearch.pl
    2. First fw1logsearch – all conditions must be true for any events to match
    Source address must NOT be in any of the following regex ranges:
    10.1.11.* 10.1.13.* 10.1.15.* 10.1.19.*
    10.2.10.* 10.2.11.*
    192.168.22.* 192.168.24.* 192.168.25.*
    Destination address must be in one of the same following regex ranges.
    Service (destination port) must be one of:
    Exactly port: 1310, 1411, 1812, or any port starting with 455
    No protocol is specified, so it will match either TCP or UDP

    fw1logsearch.pl will output any matching events to stdout, including a FW1 log header line, so the next instance of fw1logsearch.pl continues filtering the result set.

    3. The second fw1logsearch.pl specifies Source Address must not be any of the following
    192.168.22.14

    10.2.11.12

    4. The last fw1logsearch.pl excludes port 1310 from 192.168.24.12, and puts all those records into a separate reject file, while writing the other records to stdout.

    This script has been used to process over 4 billion records within the project I wrote it for – and precisely found all the use of particular business cases I needed to modify.  The result was zero outages and no unintended business interruption.

    Basic syntax/help file:

    Usage:  fw1logsearch.pl
    [-a|--incaction|-A|--excaction <action regex>]
    [-p|--incservice|-P|--excservice <dst port regex>]
    [-b|--incs_port|-B|--excs_port <src port regex>]
    [-s|--incsrc|-S|--excsrc <src regex>]
    [-d|--incdst|-D|--excdst <dst regex>]
    [-o|--incorig|-O|--excorig <fw regex>]
    [-r|--incrule|-R|--excrule <rule-number regex>]
    [-t|--incproto|-T|--excproto <proto regex>]

    [--dnscache <dns-cache-file>]
    [--resolveip]
    [--allinclude]
    [--allexclude]
    [--rejectfile <file>]
    [--debug <level>]

    fw1logsearch.pl will search a fwm logexport text file for regex patterns specified for supported columns (such as service, src, dst, rule, action, proto and orig).

    Include and exclude regex matches may be specified on the same line, although they both will include (print) a line or exclude (reject) a line based on single matches.  Allinclude or Allexclude must be specified to force a match
    only on all specified column regex patterns.

    Regex patterns can be enclosed with single quotes to include characters that are special to the shell, such as the ‘or’ (|) operator.

    Header will be output only if there are any matching lines.

    Example invocations:
    $ cat 2008-07-07*txt | \
    fw1logsearch.pl \
    -p ’53|domain’ \
    -d ’192.168.1.2|host1|10.10.1.2|host2′ \
    -o ’192.168.2.3|10.10.2.4|10.10.4.5′ \
    -S ’64.65.66.67|32.33.34.35|10.10.*|192.168.*’ \
    –resolveip
    Will require destination port (service) to be 53, destination IP to be any of 192.168.1.2, host1, 10.10.1.2, or host2  the reporting firewall (origin) to be any of 192.168.2.3, 10.10.2.4, or 10.10.4.5  and the source IP must not be
    any of 64.65.66.67, 32.33.34.35, 10.10.*, or 192.168.*  Any lines that match this criteria, will display and the orig, src, and dst columns will use the default DNS cache file (dynamically built/managed) to perform name resolution, replacing the IP addresses where possible.

    Include regex patterns:
    -a  –incaction    Rule action (accept, deny)
    -b  –incs_port    Source port (s_port)
    -p  –incservice   Destination port (service)
    -s  –incsrc       Source IP|hostname
    -d  –incdst       Destination IP|hostname
    -o  –incorig      Reporting FW IP|hostname
    -r  –incrule      Rule number that triggered entry
    -t  –incproto     Protocol of connection

    Exclude regex patterns:
    -A  –excaction    Rule action (accept, deny)
    -B  –excs_port    Source port (s_port)
    -P  –excservice   Destination port (service)
    -S  –excsrc       Source IP|hostname
    -D  –excdst       Destination IP|hostname
    -O  –excorig      Reporting FW IP|hostname
    -R  –excrule      Rule number that triggered entry
    -T  –excproto     Protocol of connection

    Other options:
    –debug {level} Turn on debugging
    –dnscache      Specify location of DNS cache file to be used with
    the Resolve IPs option
    –resolveip     Resolve IPs for orig, src, and dst columns AFTER filtering
    –rejectfile    Write out all rejected lines to a specified file

    Download fw1logsearch.pl

    © 2009 Allen Pomeroy. All Rights Reserved. This is the personal website of Allen Pomeroy. Opinions expressed are not necessarily those of my employer.